fix(langflow): return None when a node is not loaded in LangChainTypeCreator classes

src/backend/langflow/interface/agents/base.py

@@ -34,6 +34,7 @@ class AgentCreator(LangChainTypeCreator):
             raise ValueError("Agent not found") from exc
         except AttributeError as exc:
             logger.error(f"Agent {name} not loaded: {exc}")
+            return None
 
     # Now this is a generator
     def to_list(self) -> List[str]:

src/backend/langflow/interface/base.py

@@ -51,7 +51,7 @@ class LangChainTypeCreator(BaseModel, ABC):
         signature = self.get_signature(name)
         if signature is None:
             logger.error(f"Node {name} not loaded")
-            return
+            return None
         if isinstance(signature, FrontendNode):
             return signature
         fields = [

src/backend/langflow/interface/chains/base.py

@@ -42,6 +42,7 @@ class ChainCreator(LangChainTypeCreator):
             raise ValueError("Chain not found") from exc
         except AttributeError as exc:
             logger.error(f"Chain {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         custom_chains = list(get_custom_nodes("chains").keys())

src/backend/langflow/interface/document_loaders/base.py

@@ -133,6 +133,7 @@ class DocumentLoaderCreator(LangChainTypeCreator):
             raise ValueError(f"Documment Loader {name} not found") from exc
         except AttributeError as exc:
             logger.error(f"Documment Loader {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/embeddings/base.py

@@ -23,6 +23,7 @@ class EmbeddingCreator(LangChainTypeCreator):
 
         except AttributeError as exc:
             logger.error(f"Embedding {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/llms/base.py

@@ -30,6 +30,7 @@ class LLMCreator(LangChainTypeCreator):
 
         except AttributeError as exc:
             logger.error(f"LLM {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/memories/base.py

@@ -31,6 +31,7 @@ class MemoryCreator(LangChainTypeCreator):
             raise ValueError("Memory not found") from exc
         except AttributeError as exc:
             logger.error(f"Memory {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/prompts/base.py

@@ -48,6 +48,7 @@ class PromptCreator(LangChainTypeCreator):
             logger.error(f"Prompt {name} not found: {exc}")
         except AttributeError as exc:
             logger.error(f"Prompt {name} not loaded: {exc}")
+        return None
 
     def to_list(self) -> List[str]:
         custom_prompts = get_custom_nodes("prompts")

src/backend/langflow/interface/text_splitters/base.py

@@ -58,6 +58,7 @@ class TextSplitterCreator(LangChainTypeCreator):
             raise ValueError(f"Text Splitter {name} not found") from exc
         except AttributeError as exc:
             logger.error(f"Text Splitter {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/toolkits/base.py

@@ -47,6 +47,7 @@ class ToolkitCreator(LangChainTypeCreator):
             raise ValueError("Prompt not found") from exc
         except AttributeError as exc:
             logger.error(f"Prompt {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return list(self.type_to_loader_dict.keys())

src/backend/langflow/interface/vectorStore/base.py

@@ -42,6 +42,7 @@ class VectorstoreCreator(LangChainTypeCreator):
             raise ValueError(f"Vector Store {name} not found") from exc
         except AttributeError as exc:
             logger.error(f"Vector Store {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return [

src/backend/langflow/interface/wrappers/base.py

@@ -25,6 +25,7 @@ class WrapperCreator(LangChainTypeCreator):
             raise ValueError("Wrapper not found") from exc
         except AttributeError as exc:
             logger.error(f"Wrapper {name} not loaded: {exc}")
+            return None
 
     def to_list(self) -> List[str]:
         return list(self.type_to_loader_dict.keys())